need more opinions ????

helo everyone,,,,i own a 95' aurora, 100,000 mi...about 2 months ago i started the car and it backfired.the check engine light immediately came on...the car was almost non-driveable..it would stall at every light,had no power and the rpm's were all over the place..i managed to make it down to the local garage,unfortunally he did not have a scanner for the 95'...his first guess was a vacuum hose,all were ok...his second guess was a sticking egr valve...i got the car home,turned it off and went inside..came out 1 hour latter,started the car and it was running 100% again.absolutely perfect....about six weeks later it did the same thing..i pulled the egr valve out,cleaned and re-installed..no improvement...i managed to get the car on the express way,performance slowly returned to normal...it's running perfect again..any more input on what the problem could be ???? i'm wondering if i just need a new egr valve ?? mine may be just shot..the vehicle also has the original fuel pressure regulator.could this be the proplem..the car is running like new again..kind of strange??

more likely the FPR than the EGR.

The EGR is designed to be open while driving but not at idle. If it should get stuck open at idle then you would have rough idle but it should not effect, to a great degree, hi-way speed driving.

If your have the original FPR then it's time; cheap, easy, do-it-yourself.

more likely the FPR than the EGR.

The EGR is designed to be open while driving but not at idle. If it should get stuck open at idle then you would have rough idle but it should not effect, to a great degree, hi-way speed driving.

If your have the original FPR then it's time; cheap, easy, do-it-yourself.
well i'm no expert,but i don't think the fpr would have that much of a drastic effect on the cars performance ??? this is much worse then a rough idle.the vehicle is almost non-driveable ????

I agree but it's a good place to start...

Without the codes it's tough to know what else to look at. Plug, wires, MAF, Coils, Crank Sensor all possibilities.

A catastophic failure of the FPR will dump so much fuel into the intake that there is no way the PCM could compensate and the resulting performance degradation would be far greater than just "rough idle"

There is of course the backfire flap behind the PS pump on the intake manifold that is prone to get stuck open as well. This would create a LARGE vac leak that most mechanics would not look for.

any more input or opinions ????

How about just some bad gas?

Have you run any fuel system cleaner through it yet?

Dunno - typically fuel issues do not set codes. However, contaminated fuel could become concentrated into the pick-up area in the tank when taking a turn and then be drawn into the fuel system at a level that could cause temporary severe drivablity issues and could set missfire and mixture codes.

Have you done the FPR yet?

how about you check the side of the intake manifold that the throttle body isn't on. Spray some carb cleaner around that area when the idle is rough. It might help it. There is a valve that has a seal and when that seal goes bad it sounds alot like the problems you are experiencing. The valve keeps the car from back firing. So if the seal is bad air is getting in the intake causing a bad air fuel mixture so since that was malfunctioning then that valve might have something to do with the backfiring as for the stalling out and then on the highway doing fine I had the same thing happened to me. You can replace the seal around the valve but Im not sure if GM would just have that part to sell they want to make the most money out of parts like that so they'll make you buy the whole intake plenium. That part at the dealer is 400 bucks or more. Get the part number and check gmpartsdirect.com that should cut your price significantly. Hope thats some good advice.

When I had a problem like that it was my plug wires, they were getting bad. Now I have a problem with it drinking gas and stalling all the time, but it runs smooth. I would like to now if anyone knows anything about a part that is on the passenger side of the car, back towards the firewall. It is just before the plug and next to the coil packs. It has spots for three lines going to it. One line goes across the back of the engine underneath the plug wires and connects to some connector piece that goes to the fuel lines on the right back by the firewall. This part has three places to plug lines in, but there is only one plugged in. Does anyone now where the others go?

pictures?

I believe that's the MAP sensor. It should only have one vac line; the others are a valve and a vent. However, on my '97 that one vac line connects to the front of it and then goes under the engine cover to the place you described; connecting to another sensor next to the EGR valve on the way.


do you have a check engine light?
if it cranks too long to start sometimes and drinks too much gas then you probably need a new FPR
http://www.howardm.net/dred98/fpr.php

have you replaced your air filter lately?

Speaking of EGR valves...does the 02 3.5 have two of them?

Yes, there is a check engine light. It say's that it is the mass air flow sensor. I will probably end up buying one, but I don't think that it is the problem. The part that I am talking about, with it going to the fuel lines, makes me think that it is the problem. I found where one line goes. I got to look at another one the same year, But as always the part that I'm talking about looked different on that car. Theirs looked like a cylinder type, but it still had 2 lines so I found where the one goes, it ends up in the same connector as the other, where the fuel lines go.
My part looks kinda like an older relay type, except with thoughs lines.
Does anyone know anything about 4.6 cougars. I'm having a rough time with cars lately. Bikes are starting to sound muck better. lol

This is of course a fuel injected car, and a very common mistake that people make is to step on the gas pedal while starting the car....I'm not insinuating that you have done this, just a thought....

This causes a lean condition and often a backfire. If this has happenned a few times, it may have damaged the Mass Air Flow Meter...... or created a large vaccuum leak which would only aggravate the problem further......

My wife drives the car mostly. She has had a fuel injected car for years, I wouldn't thank that she would do that, but who knows.
I'll have to get it if I can get out of work in time.

Well, I bought the mass air flow sensor for my aurora. That wasn't the problem, even though it says that it is on the computer that they plug it into at auto zone and advance auto. Still looking at the part on the passenger side. I think that it must be it. I'm going to try to make it to the dealers tuesday.

I had a TPS that was covered in carbon after I had a head gasket blow and then the engine replaced. They never cleaned the sensor when they replaced the engine. It was having very similar conditions that you describe. I took the throttle body off, cleaned all the sensors an surfaces in the throttle body and then the car ran great. No surges or stalling whatsoever. Cleaned the egr too.